Threat of Slides Rises as Storms Approach

Weather: Workers try to shore up collapsed San Fernando Valley hillside. First deluge is expected today.

Three powerful Pacific storms were bearing down on Los Angeles late Friday, bringing the likelihood of more drenching rain--and the threat of more mudslides, flooding and punishing surf--to already sodden Southern California.

The first storm, following what meteorologists called a "classic El Nino scenario," was expected to slam into the Southland about noon today as efforts continued to shore up a rain-soaked San Fernando Valley hillside that collapsed before dawn Friday, tearing away a garage and forcing the evacuation of five homes.

Meteorologist Kevin Stenson said the first storm is expected to dump 1 to 4 inches of wind-driven rain on the Los Angeles Basin today and Sunday, with most of it falling in a two- to three-hour period as the main storm front passes through the Southland early this afternoon.

"It looks quite rough," the meteorologist said.

Scattered showers and possible thundershowers are expected to continue through Sunday, and after a short break Monday, a second storm is due to invade Southern California on Monday night or early Tuesday.

"The second one is heading right for L.A., and it looks just as intense as the first one," said Stenson, an employee of WeatherData Inc., which provides forecasts for The Times. "There should be another break on Wednesday and early Thursday, but by Thursday night, here comes the third one. Right now, the third one looks like the strongest of the three."

Local officials were bracing for an onslaught.

"We're getting our swift-water rescue teams activated--probably all 11 of them--with helicopters, divers and all their equipment," said Inspector Henry Rodriguez, a spokesman for the Los Angeles County Fire Department. "We've got bulldozers at Zuma, building up the [sand] berms to help protect oceanfront homes."

Donna Guyovich, a spokeswoman for the county's Department of Public Works, said flood-control personnel were making sure that debris basins and storm channels are clear and ready to handle the expected runoff.

"Reservoirs are being lowered to provide extra capacity," she said. "Road crews are being stationed below brush fire burn zones and other areas threatened by mudslides."

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Friday's mudslide in West Hills occurred about 2:30 a.m., when a collapsing hillside ripped a 200-foot-long, 30-foot-deep gash under the house of Lou and Reata Vaughn, leaving their bedroom dangling over a chasm.

City building officials said that if the home had not undergone a seismic retrofitting after the 1994 Northridge earthquake, it would have tumbled into a muddy ravine.

In the damp of Friday morning, as they and their pajama-clad neighbors stood in the middle of the street marveling at the wreckage, the Vaughns could only be grateful for the quake they had once cursed.

"If I had my wits about me," said Lou Vaughn, 66, "I'd be crying."

The West Hills mudslide prompted the evacuation of the Vaughns' and four other homes and threatened several other residences farther down the hill.

Because of the hazard, city officials took the unusual step of temporarily shoring up the privately owned hillside. Plans called for draping the affected area with plastic sheeting, draining away as much of the water as possible and driving in pilings to stabilize the ground.

With more rains expected, officials urged residents to make sure that water is draining properly from their property. The officials recommended clearing roof gutters and drains and, when necessary, draping bare slopes with tarpaulins.

"The hillsides are moving," warned David Keim, the city's principal building inspector. "The mud wants to slide like on a ski slope."

The West Hills landslide was typical of the problems that can occur in the Los Angeles area, geologists said.

Many homes are built on slopes underlain by siltstone bedrock. After a hard rain, water begins saturating the soil above the siltstone. When the water reaches the siltstone--a process that usually takes several days--the bedrock begins to soften. The combination of heavy, water-soaked soil and crumbling bedrock creates conditions susceptible to landslides.